This page offers guidance to potential users of digital CCTV systems, where the pictures are intended to be used by the police or are likely to be used in an investigation. For CCTV recordings to be effective in detecting and investigating crime they must be fit for purpose and easily accessible by police investigators. For digital CCTV there are four main areas that must be considered:
How many pictures per second?
1. Specify your requirement – decide what you want to see and where,and select a system that will do it.
2. View the recorded pictures or print out,not the live screen,to assess the system performance.
3. The system clock should be set correctly and maintained (taking account of GMT and BST).
4. Picture quality should not be reduced to fit the available storage capacity of the system.
5. Regular maintenance should be conducted on all aspects of the system.
What should I keep?
How should I keep it?
6. The system should be operated and recorded pictures retained in a secure environment.
7. Electronic access controls,such as passwords or encryption,should not prevent authorised access to the system or recordings.
8. The system should have sufficient storage capacity for 31 days good quality pictures.
9. The system should be capable of securing relevant pictures for review or export at a later date.
How much video should the system export and in what format?
10. A system operator should be available who is able to replay and export recordings.
11. A simple system operator’s manual should be available locally to assist with replay and export.
12. The operator should know the retention period of the system and export time for various amounts of data.
13. The system should be able to quickly export video and stills to a removable storage-medium,with time and date integral to the relevant picture.
14. Export should include any software needed to view or replay the pictures.
15. The system should have an export method proportionate to the storage capacity.
16. Pictures should be exported in the native file format at the same quality that they were stored on the system.
Can the pictures be easily viewed?
17. The playback software should:
• have variable speed control including frame by frame, forward and reverse viewing;
• display single and multiple cameras and maintain aspect ratio i.e. the same relative height and width;
• display a single camera at full resolution;
• permit the recording from each camera to be searched by time and date;
• allow printing and/or saving (e.g. bitmap) of pictures with time and date.
18. The time and date associated with each picture should be legible.
19. Once exported to removable media it should be possible to replay the files immediately.